package com.xinkao.example.util.easyexcel;

import com.alibaba.excel.metadata.CellData;
import com.alibaba.excel.metadata.Head;
import com.alibaba.excel.write.handler.CellWriteHandler;
import com.alibaba.excel.write.metadata.holder.WriteSheetHolder;
import com.alibaba.excel.write.metadata.holder.WriteTableHolder;
import lombok.Data;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellType;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.util.CellRangeAddress;

import java.util.List;

/**
 * 单元格合并
 *
 * @author Jamin
 * @date 2020/11/9 11:35
 */
@Data
public class CellMergeHandler implements CellWriteHandler {
	/**
	 * 合并字段的下标
	 */
	private List<Integer> mergeColumnIndex;
	/**
	 * 合并几行
	 */
	private int mergeRowIndex;

	public CellMergeHandler() {
	}

	public CellMergeHandler(int mergeRowIndex, List<Integer> mergeColumnIndex) {
		this.mergeRowIndex = mergeRowIndex;
		this.mergeColumnIndex = mergeColumnIndex;
	}

	@Override
	public void beforeCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Row row,
	                             Head head, Integer integer, Integer integer1, Boolean aBoolean) {

	}

	@Override
	public void afterCellCreate(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder, Cell cell,
	                            Head head, Integer integer, Boolean aBoolean) {

	}

	@Override
	public void afterCellDataConverted(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder,
	                                   CellData cellData, Cell cell, Head head, Integer integer, Boolean aBoolean) {

	}

	@Override
	public void afterCellDispose(WriteSheetHolder writeSheetHolder, WriteTableHolder writeTableHolder,
	                             List<CellData> list, Cell cell, Head head, Integer integer, Boolean aBoolean) {
		//当前行
		int curRowIndex = cell.getRowIndex();
		//当前列
		int curColIndex = cell.getColumnIndex();

		if (curRowIndex > mergeRowIndex) {
			for (int i = 0; i < mergeColumnIndex.size(); i++) {
				if (curColIndex == mergeColumnIndex.get(i)) {
					mergeWithPrevRow(writeSheetHolder, cell, curRowIndex, curColIndex);
					break;
				}
			}
		}
	}

	private void mergeWithPrevRow(WriteSheetHolder writeSheetHolder, Cell cell, int curRowIndex, int curColIndex) {
		//获取当前行的当前列的数据和上一行的当前列列数据，通过上一行数据是否相同进行合并
		Object curData = cell.getCellTypeEnum() == CellType.STRING ? cell.getStringCellValue() :
				cell.getNumericCellValue();
		Cell preCell = cell.getSheet().getRow(curRowIndex - 1).getCell(curColIndex);
		Object preData = preCell.getCellTypeEnum() == CellType.STRING ? preCell.getStringCellValue() :
				preCell.getNumericCellValue();
		// 比较当前行的第一列的单元格与上一行是否相同，相同合并当前单元格与上一行
		if (curData.equals(preData)) {
			Sheet sheet = writeSheetHolder.getSheet();
			List<CellRangeAddress> mergeRegions = sheet.getMergedRegions();
			boolean isMerged = false;
			for (int i = 0; i < mergeRegions.size() && !isMerged; i++) {
				CellRangeAddress cellRangeAddr = mergeRegions.get(i);
				// 若上一个单元格已经被合并，则先移出原有的合并单元，再重新添加合并单元
				if (cellRangeAddr.isInRange(curRowIndex - 1, curColIndex)) {
					sheet.removeMergedRegion(i);
					cellRangeAddr.setLastRow(curRowIndex);
					sheet.addMergedRegion(cellRangeAddr);
					isMerged = true;
				}
			}
			// 若上一个单元格未被合并，则新增合并单元
			if (!isMerged) {
				CellRangeAddress cellRangeAddress = new CellRangeAddress(curRowIndex - 1, curRowIndex, curColIndex,
						curColIndex);
				sheet.addMergedRegion(cellRangeAddress);
			}
		}
	}
}
